[12] This fact is analogous to our common experience of being awaked by a loud noise and then hearing it after we awake; yet the explanation is not the same.
Again, the same phenomenon to an equally marked degree attended the sound of her breathing. It is well enough known that the smallest functional bodily changes induce changes in both the rapidity and the quality of the respiration. In sleep the muscles of inhalation and exhalation are relaxed, inhalation becomes long and deep, exhalation short and exhaustive, and the rhythmic intervals of respiration much lengthened. Now degrees of relative wakefulness are indicated with surprising delicacy by the slight respiration sounds given forth by the sleeper. Professional nurses learn to interpret these indications with great skill. This exaltation of hearing became very pronounced in my operations with the child. After some experience the peculiar breathing of advancing or actual wakefulness in her was sufficient to wake me. And when awake myself the change in the infant's respiration sounds to those indicative of oncoming sleep was sufficient to suggest or bring on sleep in myself. In the dark, also, the general character of her breathing sounds was interpreted with great accuracy in terms of her varied needs, her comfort or discomfort, etc. The same kind of suggestion from the respiration sounds now troubles me whenever one of the children is sleeping within hearing distance.[13]
[13] This is an unpleasant result which is confirmed by professional infants' nurses. They complain of loss of sleep when off duty. Mrs. James Murray, an infants' nurse in Toronto, informs me that she finds it impossible to sleep when she has no infant in hearing distance, and for that reason she never asks for a vacation. Her normal sleep has evidently come to depend upon continuous soporific suggestions from a child. In another point, also, her experience confirms my observations, viz., the child's movements, preliminary to waking, awake her, when no other movements of the child do so—the consequence being that she is ready for the infant when it gets fully awake and cries out.
The reactions in movement upon these suggestions are very marked and appropriate, in customary or habitual lines, although the stimulations are quite subconscious. The clearest illustrations in this body of my experiences were afforded by my responses in crude songs to the infant's waking movements and breathing sounds. I have often waked myself by myself singing one of two nursery rhymes, which by endless repetition night after night had become so habitual as to follow in an automatic way upon the stimulus from the child. It is certainly astonishing that among the things which one may get to do automatically, we should find singing; but writers on the subject have claimed that the function of musical or semi-musical expression may be reflex.
The principle of subconscious suggestion, of which these simple facts are less important illustrations, has very interesting applications in the higher reaches of social, moral, and educational theory.
Inhibitory Suggestion.—An interesting class of phenomena which figure perhaps at all the levels of nervous action now described, may be known as Inhibitory Suggestions. The phrase, in its broadest use, refers to all cases in which the suggesting stimulus tends to suppress, check, or inhibit movement. We find this in certain cases just as strongly marked as the positive movement—bringing kind of suggestion. The facts may be put under certain heads which follow.
Pain Suggestion.—Of course, the fact that pain inhibits movement occurs at once to the reader. So far as this is general, and is a native inherited thing, it is organic, and so falls under the head of Physiological Suggestion of a negative sort. The child shows contracting movements, crying movements, starting and jumping movements, shortly after birth, and so plainly that we need not hesitate to say that these pain responses belong purely to his nervous system; and that, in general, they are inhibitory and contrary to those other native reactions which indicate pleasure.
The influence of pain extends everywhere through mental development, however. Its general effect is to dampen down or suppress the function which brings the pain; and in this its action is just the contrary to that of pleasure, which furthers the pleasurable function.
Control Suggestion.—This covers all cases which show any kind of restraint set upon the movements of the body short of that which comes from voluntary intention. The infant brings the movements of his legs, arms, head, etc., gradually into some sort of order and system. It is accomplished by a system of organic checks and counter-checks, by which associations are formed between muscular sensations on the one hand and certain other sensations, as of sight, touch, hearing, etc., on the other hand. The latter serve as suggestions to the performance of these movements, and these alone. The infant learns to balance his head and trunk, to direct his hands, to grasp with thumb opposite the four fingers—all largely by such control suggestions, aided, of course, by his native reflexes.